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TPS6755: Looking for an inverting DC/DC converter

Kazuhiko Hirano
Genius 15068 points
Part Number: TPS6755
Other Parts Discussed in Thread: PMP20371

Tool/software:

Hello,

My customer is looking for an inverting DC/DC converter to meet the following requirements. TPS6755 does not meet required voltage range. Does TI have any recommended devices?
  Vin=-48V
  Vout/Iout=+12V/0.5A

Best regards,

K.Hirano

  • 0
    TI__Guru 65310 points

    Hello Kazuhiko Hirano,

    At the end you need a boost converter for more than 60V. An example with a lot more output power could be this one: PMP20371 reference design | TI.com

    Please review the schematic. At the end, this is a boost converter which has the -48V as reference level and needs the output voltage level translator shown in the lower right area of the schematic.

    The design of the FB circuit could be taken as is, but the power stage would needed to be re-designed. If you would use the calculator, you would design the power stage as if the output voltage is 12V more than the input voltage.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Genius 15068 points

    Brigitte,

    Thank you for your response.
    But I am not an expert of power devices, I would like to know more details about how to modify the PMP20371 for my customer's requirements.
    Please explain how to do it step by step.
    And, what is the calculator? Where can I get it?

    Best regards,

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Guru 65310 points

    Hello Kazuhiko,

    The calculator can be found here: LM5122-BOOST-CALC Calculation tool | TI.com

    For the necessary changes, please fill in the calculator with just a small variation on the input voltage and use 60V as output voltage. Then you should get the right components for the power stage and the compensation.

    Then I recommend ordering the EVM, adding the circuit that is in addition on the FB node and check it out in the lab.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    TI__Genius 15068 points

    Brigitte,

    Can customer also use WeBench simulation with the following conditions to calculate component values?
    Vin = 48V
    Vout/Iout = 60V/0.5A

    Best regards,

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Guru 58641 points

    Hi Kazuhiko,

    no, you can also use Webench for that as it does not give you a control option for the external logic.

    For the power stage part itself (inductor, sense resistor, MOSFET) you might could use Webench if you have the right input parameters.

    The quickstart calculator just provides more control and can help to better optimize the design for the target application.

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    TI__Guru 58641 points

    Hi Kazuhiko,

    i assume input should still be -48V as in the first thread and not +48V as in the last one.

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    TI__Genius 15068 points

    Stefan,

    Thank you for your suggestions.
    Since WeBench does not accept -48V Vin, I use Vin = 48V and Vout/Iout = 60V/0.5A for Webanch.
    Then, I would like to put the component values in the WeBench to the calculator, then fine tune it.

    Best regards,

    K.Hirano

  • +1 in reply to Kazuhiko Hirano
    TI__Guru 65310 points

    Hello K.Hirano,

    This sounds like a good plan, but you could as well use the calculator directly.

    Best regards,
    Brigitte